In the sport of bowling, the angle at which a bowling ball strikes the head pin is an important factor in its effect on the pins, that is, the number of pins knocked down by the bowling ball. Proficient bowlers prefer a bowling ball that consistently describes a curve or “hook” as it approaches the pins. If the hook of the ball begins too soon or too late as the ball moves down the lane towards the pins, what is called the hook effect changes and the ability of the ball to knock down a maximum number of pins may be diminished.
Of particular importance is the ability of the ball to hook near the end of the bowling lane in front of the pins when the ball is thrown with a spin. A bowling ball that hooks well is highly desirable since it gives the bowler an advantage over competing bowlers. Modern bowling balls are formed with a center core of a plastic composition material surrounded by a coverstock which is usually formed of a polyurethane. The polyurethane contains a plasticizer which is the most important component contributing to the ability of the bowling ball to hook. Most of the lanes on which bowling is conducted are oiled at least in the area where the bowling ball first engages the lane after it is released by the bowler. It has been generally believed in the bowling community that oil applied to the lanes is absorbed by the bowling ball and that this absorption of oil into the coverstock of the bowling ball reduces the hooking effect of the bowling ball. Efforts in the bowling community to restore the hooking effect of a bowling ball have been directed primarily to the removal of the absorbed lane oil from the bowling ball, particularly removing oil from the coverstock of the bowling ball. Such efforts proposed by the bowling community have been as extreme as heating the bowling ball to drive off the absorbed oil or treating the coverstock with harmful or dangerous chemicals.
It has been discovered that the degradation of the performance of a bowling ball that is, the reduction in its ability to hook properly because of continued play of the bowling ball on oiled lanes, is not due solely to the absorption of oil as has been conventional wisdom in the bowling community but is due to the concentration of plasticizers in areas of the bowling ball contiguous to the outer surface of the coverstock. It has been discovered the plasticizer in the coverstock concentrates in microchannels which are formed near the outer surface of the porous coverstock as the bowling ball originally engages and continues in ever changing contact with the lane as the ball rolls down the lane. This contact between the bowling ball and the lane forms concentrations of plasticizers in localized areas of the coverstock.